Physicochemical and Functional Properties of Casein Phosphopeptide–Chitosan Oligosaccharide Nanocomplexes as Calcium Absorption Enhancers

Enhancing intestinal calcium absorption in the elderly is essential for reducing the risk of osteoporosis. The purpose of this study was to manufacture calcium-containing casein phosphopeptide (CPP)-chitosan oligosaccharide (CSO) nanocomplexes and determine their physicochemical properties (e.g., particle size) and functional characteristics (e.g., intestinal calcium absorption and entrapment efficiency). CPP-CSO nanocomplexes with particle sizes of less than 200 nm were successfully formed. The particle size of the CPP-CSO nanocomplexes increased with increasing CPP concentration, whereas their zeta potential value decreased. Increasing the pH from 5.5 to 6.6 led to a decrease in the particle size, and the zeta potential values decreased accordingly. Caco-2 cells exhibited no cytotoxicity at the various nanocomplex concentrations. The intestinal calcium absorption of the CPP-CSO nanocomplexes increased with a decrease in CPP concentration and an increase in pH. A negative correlation was found between calcium absorption and the particle size of CPP-CSO nanocomplexes. In conclusion, the CPP concentration and pH are manufacturing factors that affect the physicochemical properties of CPP-CSO nanocomplexes.